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Flashcards in Heavy Machine Guns Deck (96):
1

The Browning machine gun caliber .50 HB, M2 is a

belt-fed, recoil-operated, air-cooled, crew-served machine gun.

2

The gun is capable of

single shot, as well as automatic fire, and operates on the short recoil principle.

3

The machinegun is capable of being fed from

either the right or left by repositioning certain parts

4

The M2 .50 caliber machine gun has a leaf-type

rear sight, graduated in both yards and mils. The scale ranges from 100 to 2,600 in yards and from 0 to 62 in mils.

5

The windage knob permits

deflection changes to right or left of center

6

the M2 .50 caliber machine gun reciever, barrel and tripod weigh a total of

128 pounds

7

the M2 .50 caliber machine gun reciever with barrel installed is how long

65 inches

8

for the M2 .50 caliber machine gun rates of sustained fire are

Less than 40 rounds per minute (rpm)

9

for the M2 .50 caliber machine gun rates of rapid fire are

40 or more rpm

10

for the M2 .50 caliber machine gun rates of cyclic fire are

450-550 rpm

11

Maximum range for the M2 .50 caliber machine gun

7400 meters

12

Maximum Effective range for the M2 .50 caliber machine gun is

1830 meters

13

Grazing fire range for the M2 .50 caliber machine gun is

700 meters

14

M2 – Dummy ammunition Characteristics are

 Plain
 Holes in cartridge

15

M2 .50 Caliber Machine Gun Ammunition types are

M2 – Dummy
M1, M1A1 – Blank
M2, M33 – Ball
M1, M10, M17 – Tracer
M1, M23 – Incendiary
M2 – Armor piercing
M8 – Armor-piercing incendiary
M20 – Armor-piercing incendiary-tracer
M903 – Sabot light armor penetrator
M962 – Sabot light armor penetrator-tracer

16

M1, M1A1 – Blank characteristics are

No bullet, crimped cartridge

17

M2, M33 – Ball characteristics are

Plain

18

M1, M10, M17 – Tracer characteristics are

Red, orange, or brown tip

19

M1, M23 – Incendiary characteristics are

Blue tip

20

M2 – Armor piercing characteristics are

Black tip

21

M8 – Armor-piercing incendiary characteristics are

Aluminum tip

22

M20 – Armor-piercing incendiary-tracer characteristics are

Aluminum tip with red ring

23

M903 – Sabot light armor penetrator characteristics are

Amber tinted round

24

M962 – Sabot light armor penetrator-tracer characteristics are

Red tinted round

25

The purpose of the Barrel group on the M2 .50 Caliber Machine Gun is

 Houses cartridges for firing
 Directs projectile

26

M2 .50 Cal Carrier assemblys purpose is

Provides handle to:
 Carry barrel
 Remove barrel from the receiver

27

he purpose of Backplate group on M2 .50 Cal is

Houses the:
 Trigger
 Bolt latch releases lock
 Buffer tube sleeve
 Left and right spade grips

28

The purpose of the Cover group on the M2 .50 Cal is

 Feeds linked belt ammunition
 Positions and holds cartridges in
position for extracting, feeding, and
chambering

29

The purpose of the Bolt group on the M2 .50 Cal is

Provides feeding, chambering, firing,
and extracting, using the propellant
gases and recoil spring for power

30

the purpose of the Receiver group of the M2 .50 Cal is

 Serves as support for all major components
 Houses action of weapon, which controls functioning of weapon

31

The purpose of the Bolt stud on the M2 .50 Cal is

Provides a means to move the bolt to the rear with the retracting slide handle

32

The purpose of the Barrel extension group of the M2 .50 Cal is

Secures the barrel to the recoiling parts

33

The purpose of the Barrel buffer body on the M2 .50 Cal is

Assists in recoil and counter-recoil of the bolt group

34

The purpose of the Driving spring rod assembly for the M2 .50 Cal is

Drives the bolt forward when the bolt latch release is depressed

35

The M2 .50 caliber machine gun has no

safety

36

Condition 1 for the M2 .50 caliber machine gun is

 Bolt forward
 A round in the chamber
This condition is also referred to as full load

37

Condition 2 of the M2 .50 caliber machine gun is

 Bolt forward on an empty chamber
 Rounds all the way against the cartridge stop
This condition is also referred to as half load

38

Condition 3 of the M2 .50 caliber machine gun is

 Bolt forward on an empty chamber
 Rounds inserted and held in place by the belt feeding pawl

39

Condition 4 of the M2 .50 caliber machine gun is

 Bolt forward on an empty chamber
 No source of ammunition

40

3 steps in Unloading & Clearing the M2 .50 Cal are

1
Ensure the barrel is cold. If hot (150 rounds in 2 minutes or less), let the weapon sit for 15 minutes.
2
Place weapon in single shot mode. Lock the bolt to the rear by pulling the retracting slide handle to the rear while maintaining positive control.
3
Open the top cover and remove the source of ammunition. Inspect the chamber to ensure it is clear.

41

steps to execute "LOAD" taking the M2 .50 caliber machine gun from condition 4 to condition 2 are

1
Point the weapon in a safe direction. Ensure weapon is in single shot mode.
2
Ensure the weapon is in condition 4:
 No rounds inserted anywhere in the weapon
 Bolt forward
 An empty chamber
3
Raise cover, lift extractor ejector, and slightly pull bolt to the rear.
4
Insert the double loop end of the belt in the feedway until the rounds meet the cartridge stop and place the extractor ejector between the first and second rounds. Close cover. Weapon is now half-loaded.

42

the steps to execute "MAKE READY" taking the M2 .50 caliber machine gun from condition 2 to condition 1 are

1
Point the weapon in a safe direction.
2
Ensure the bolt latch release is locked down. Ensure the weapon is on automatic.
3
Pull the retracting slide handle to the rear and release it.
CAUTION: The weapon is fully loaded.

43

the steps to execute "UNLOAD/CLEAR GUN" taking the M2 .50 caliber machine gun to condition 4 are

1
Ensure the barrel is cold. If hot (150 rounds in 2 minutes or less), let the weapon sit for 15 minutes.
2
Point the weapon in a safe direction and ensure weapon is in single shot mode
3
Unlock the bolt latch release.
4
Raise the cover.
5
Remove the ammunition from the feedway.
6
Pull the retracting slide handle to the rear until it locks.
7
Examine the chamber and T-slot to ensure they are clear of ammunition.
8
Insert a cleaning rod in the muzzle end of the barrel and push it through the bore until it can be seen in the receiver ensuring that the weapon is clear.
9
Return the retracting slide handle forward and depress the bolt latch release sending the bolt forward. Close the cover.

44

Malfunctions of the M2 .50 Cal are

Failure to function freely
Uncontrolled Automatic Fire
Stoppage

45

Failure to function freely is

Sluggish operation is usually due to human failure to eliminate excessive friction caused by
o Dirt
o Lack of proper lubrication
o Burred parts
o Incorrect headspace adjustment
o Incorrect timing

46

Uncontrolled Automatic Fire is

(runaway gun) is when fire continues even when the trigger or trigger control mechanism is released. If the cause is present before the gun is fired, the gun will start to fire when the recoiling groups move into battery the second time.

47

A runaway gun may be caused by

o A bent trigger lever, forward end of the trigger lever sprung downward
o Burred beveled contacting surfaces of the trigger lever and sear
o A jammed or broken side-plate trigger

48

To stop the uncontrolled automatic fire you should

o Keep the gun laid on target.
o Twist the belt, causing the gun to jam.
CAUTION: Do not unlatch the cover.
 Wait 15 minutes to guard against cook off.
 Clear weapon.
 Replace broken, worn, or burred parts.
 Check the side-plate trigger and trigger control mechanism, when applicable.

49

A stoppage is

any interruption in the cycle of operation caused by the faulty action of the gun or ammunition

50

Types of stoppages are

Failure to Feed
Failure to Chamber
Failure to Lock
Failure to Fire
Failure to Unlock
Failure to Extract
Failure to Eject
Failure to Cock

51

Immediate action is

the prompt action taken by the gunner without investigating the cause. The gunner performs immediate action; however, every crewmember must be trained to apply immediate action.

52

the steps to follow to reduce most stoppages without analyzing their cause in detail are

1
Yell, “Misfire!” to inform the gun line that you have a stoppage or malfunction.
2
Wait 5 seconds for the possibility of a hang fire.
3
Within the next 5 seconds, pull the bolt to the rear and watch for feeding and ejecting.
4
If feeding and ejecting occur, aim in and attempt to fire. If weapon
Fires continue mission.
Fails to fire, determine whether or not you have a hot barrel. If so, wait 15 minutes for barrel to reach air temperature.
NOTE: You have a hot barrel if it has fired 150 rounds or more in 2 minutes or less.
5
Once the barrel cools, proceed to remedial action

53

Remedial action is

the detailed examination of the weapon and ammunition to determine the cause of the stoppage

54

Removal of a cartridge from the T-Slot If the cartridge does not fall out during immediate action is

 Put the weapon on single shot and pull the bolt to the rear.
 Hold the bolt to the rear
 With the extractor raised, use a cleaning rod to push the cartridge out the bottom of the receiver, or reach under the gun and push the round up out of the T-slot

55

To Remove a ruptured cartridge you

 Raise the cover and pull the bolt to the rear.
 Place the ruptured cartridge extractor in the T-slot of the bolt in the same manner as that of a cartridge, so that it is held in line with the bore by the ejector of the extractor assembly of the gun.
 With the extractor aligned with the bore and held firmly in the T-slot, let the bolt go forward into the ruptured case; the shoulders will spring out in front of the case.
 Pull the bolt to the rear and remove the ruptured case and extractor.

56

Disassembly of the M2 .50 Cal consists of

removing the major groups
and assemblies for inspection and cleaning

57

the eight major groups that must be disassembled in the order they should be removed for the M2 .50 Cal are

1 Barrell Group
2 Back-Plate Group
3 Driving Spring Rod Assembly
4 Bolt Group
5 Barrel Extension
6 Barrel Buffer Assembly
7 Barrel Buffer Assembly
8 Receiver Group

58

Function Check steps are

1
Place the weapon in the single-shot mode.
2
With the cover closed, lock the bolt to the rear (bolt should stay to rear while in the single-shot mode).
3
Return retracting slide handles to full forward position and press the bolt latch release.
4
Press down on the trigger; weapon should fire. (Check T-slot to ensure that firing pin does protrude.) Open the cover.
5
Place the weapon in the automatic-fire mode.
6
Pull the retractor slide handle to the rear and release. (Bolt should not lock to rear.)
7
Make sure firing pin does not protrude.
8
Press trigger; weapon should fire.
9
Make sure firing pin does protrude.

59

Disassemble, clean, and oil the gun in a clean, dry location. If possible, when not in use, keep the gun covered with a

o Gun cover
o Canvas
o Tarpaulin
o Poncho

60

What do you use to clean the machine gun

Use CLP to clean the machine gun. As its name implies, it cleans, lubricates, and preserves all in one application. After cleaning the gun with CLP, wipe it dry and reapply a thin coating

61

Rifle bore cleaner (RBC) is a

cleaning solvent, which can be used to clean powder residue, carbon, and dirt from weapons. RBC does not preserve or lubricate a weapon
Use RBC and oil only when CLP is not available

62

When you inspect the machine gun, it should

be completely disassembled. Look for dirt, cracks, burrs, and rust

63

When inspecting the barrel check for

Be sure that the bore and chamber are:
 Free of rust
 Clean
 Lightly oiled.

64

When inspecting the moving parts check for

Be sure moving parts are clean and lightly oiled.
 Operate the retracting slide handle and bolt latch release several times to see that the parts function without excessive friction.

65

When inspecting Headspace and timing check for

Using the gauges, check to ensure that headspace and timing are correct.

66

When inspecting Rear sight and windage knob check for

Be sure the sight:
 Is in good condition
 Clean
 Free of grease or dirt
 Lightly oiled
 Elevation is set at 1000
 Windage is set at zero
 The sight is down

67

When inspecting Mount (M3, MK64, M36, or M4) check for

Be sure that the mount
 Is clean and lightly lubricated
 Is complete
 Functions properly
 Be sure all clamps are securely tightened

68

When inspecting Spare parts and tools check for

Be sure spare parts are clean and lightly oiled
Be sure spare parts kits are complete and in good condition.
Requisition replacement parts.
Examine newly drawn parts.

69

When inspecting T&E check for

Be sure it is clean and lightly lubricated.
Be sure both hand wheels work properly.

70

When inspecting Ammunition check for

Be sure ammunition is properly stored. Ensure boxes and ammunition are in good condition and not oiled.

71

Machine Gun Headspace is

the distance between the face of the bolt and the base of the cartridge case, fully seated in the chamber

72

Machine Gun Timing is

the adjustment of the gun so that firing takes place when the recoiling parts are in the correct position for firing

73

When to Check and set headspace

o Before firing
o After assembling the gun
o After replacing the barrel or receiver group

74

Steps to set Machine gun timing are

1
Check headspace first as previously described.
2
Pull the bolt to the rear with the retracting slide handle and release to cock the machine gun.
3
Grasp the retracting slide handle and retract the bolt just enough (1/16-inch) to insert the no-fire gauge between the barrel extension and the trunnion block. Release the retracting slide handle
4
Depress the trigger; gun should not fire. NOTE: If the gun
 Does not fire, go to step 5.
 Does fire, you have early timing. Go to steps 7 through 14
5
Grasp the retracting slide handle and retract the bolt just enough to remove the no-fire gauge and insert the fire gauge in the same place. Release the retracting slide handle.
6
Depress the trigger; gun should fire. If it:
 Does, timing adjustment is now complete.
 Does not fire, you have late timing. Go to steps 7 through 14.
7
Remove the gauge, cock the gun, and return the bolt forward.
8
Insert the fire gauge.
9
Remove the backplate.
NOTE: Weapon must be in single-shot mode to remove backplate. Always place the backplate on the ground with the spade handles down to avoid damaging the trigger mechanism.
10
Screw the timing adjustment nut all the way down until it touches the trigger lever (see diagram below).
NOTE: The timing nut will come off the timing post if it is depressed too many clicks. If this happens, apply upward pressure to the timing nut while screwing it back on to the timing post.
11
Try to fire the machine gun by pushing up on the rear of the trigger lever located directly underneath the timing nut; gun should not fire.
12
Screw the timing adjustment nut up (to the right) one click at a time. Push up on the trigger lever after each click. Keep doing this until the gun fires.
NOTE: You must apply firm pressure to the trigger lever.
13
Turn the timing adjustment nut an additional two clicks to compensate for heat expansion.
14
Replace the backplate, remove the gauge, and cock the machine gun.
15
Repeat steps 3 through 6 to ensure timing is set correctly.

75

M2 .50 Caliber Machine Gun Cycle of Operations consists of what basic steps

 Feeding - The act of placing a cartridge in the receiver, approximately in back
of the barrel, ready for chambering.
 Chambering - Placing the cartridge into the chamber of the weapon.
 Locking - The bolt is locked to the barrel and barrel extension.
 Firing - The firing pin is released, igniting the primer of the cartridge.
 Unlocking - The bolt is unlocked from the barrel and barrel extension.
 Extracting - The empty cartridge case is pulled from the chamber.
 Ejecting - The empty cartridge case is expelled from the receiver.
 Cocking - The firing pin is withdrawn into the cocked position.

76

The M3 mount is a

folding tripod with three, telescopic, tubular legs connected at the tripod head

77

The T&E mechanism is used to

engage preselected target areas at night or during limited visibility conditions

78

A pintle connects

the gun to the tripod mount, M3

79

The truck mount, M36 consists of

a cradle with a roller carriage on a circular track

80

The MK64 gun cradle mount is a

vehicle mount primarily designed for the M2. However, because of its versatility, the MK64 will accept the MK19 also (using the M2 mounting adapter assembly). The MK64 is used when mounting the gun on a HMMWV.

81

The MK19 is a

belt-fed, air-cooled, blowback-operated, crew-served, fully automatic 40 mm grenade launcher

82

What must you do first before you disassemble the MK19

Clear the weapon

83

What is the sustained rate of fire for the MK19

40 rpm (3-5 round bursts

84

Where is the weapon safety located

On the sear assembly at the bottom rear of the receiver assembly

85

What is condition 1 for the MK19

Rounds inserted all the way to the round positioning block
Bolt to the rear
Round on the face of the bolt
Weapon on safe

86

When closing the top cover, in what position must the feed slide assembly be; and in what position must the bolt be to ensure proper alignment of the primary and secondary drive levers

Left; forward

87

How much armor plating, in inches, is the weapon capable of penetrating, when firing ammunition at zero degree obliquity

2

88

Within how many meters must the 40-mm HE round impact to cause casualties to exposed enemy personnel

15

89

To stop a runaway weapon, what step(s) must be taken

Unlock and lower one charging handle while keeping control of the weapon

90

What is condition 3 for the MK19

Rounds inserted past the primary feed pawl, bolt forward, no rounds on its face, weapon on safe

91

If a stoppage occurs, how long must you wait before pulling the bolt to the rear

10 seconds

92

How many rounds per burst should the gunner fire when engaging targets at the sustained rate?

3 to 5

93

What is the maximum effective range of the MK19

1500 meters

94

Which tripod is used with the MK19

M3

95

True or False
When loading the weapon, place the female link end of the ammunition belt through the feed throat and draw the ammunition into the weapon feed area

True

96

True or False
The MK64, MOD 7 gun cradle is used with the tripod and ring mounts

True